It is expected of keyboards, particularly those which, as autonomous units, constitute an auxiliary component, so to speak, of data processing systems, that they function reliably, can be exchanged at any time and integrated in an existing device configuration and that they be inexpensive.
Such conditions compel a standardization of the keyboards with the goal of achieving high production numbers and providing the prerequisites for large-scale production and mechanical assembly with as few work steps as possible and structural component parts which are simple in terms of functional design.
However, as a rule, a reduction in the quantity of structural component parts and in costs in manufacturing and assembly and manufacturing tolerances, which allows largescale manufacturing, impairs the stability and accordingly also the operating reliability, particularly where parts which are relatively large in dimension and are produced by means of injection molding are involved.
In contrast with efforts toward economical manufacturing is the fact that a high quality must also be demanded with respect to the external appearance for use of such keyboards in office environments which have constant climatic conditions and where the risk of soiling is relatively low, in the teller window of banks and the like, and that, when used in the area of manufacturing, in filling stations, in storage spaces and on construction sites, where negative environmental influences predominate, the functions of the keyboards must be designed for conditions of use which are severe under certain circumstances and must not be destroyed by environmental influences.
Keyboards used in trade generally correspond to the demands for quality in aesthetic and functional respects in the office environment. Under more severe conditions of use and operation, these keyboards are often unsatisfactory as a result of temperature-dependent expansions. These are essentially caused by the classical construction of the keyboards with a plurality of structural component parts which are screwed together. To this extent, the construction of the known keyboards can also not meet the requirements of a large-scale production with subsequent mechanical assembly.